So it seems squid also leave fingerprints. How long before we start tracking them in a centralized database? After all, they might travel through international waters and we don't know what kind of ideas they could carry to our coasts.

No, I agree it's a stretch, though perhaps no more of a stretch than assuming a squid was stuck on the boat for all that distance either. But stranger things have happened.

Funny, this is like underwater crop circles. Soon maybe there'll be an industry of experts who judge which squid pucker marks are authentic and which are hoaxes. Also "The Squid Puckers" might be a good name for a band...

What a drag. But seriously, the story doesn't make a lot of sense to me.

"...most important of all, something had slowed his speed down to 2 knots, even with full sails, a lot of wind, and the engine running..."

And yet, they did not look under the boat? If you're doing 2 knots under full power and having a tough time controlling the rudder, with no autopilot, seems like a good time to have a look under the hull.

"Shigeo said that his boat became so difficult to steer that, at one point, he had to issue a Mayday call to avoid a collision with a Japanese tuna boat."

Other boats around, he has steerage problems and he still is not trying to look under the boat to see what's dragging?

"We also thought that "Akitsushima" must have fouled some kind of fishing net or other junk, as no amount of barnacles could slow a modern 42-foot boat to 2 knots. But we left Nuku Hiva before we had time to dive down to look for ourselves."

Right, because a dive to look under the boat, especially the rudder, takes all of five minutes...I've been overboard 1500 miles from shore (to inspect for debris) and really it's no big deal. Besides that if you're underway and don't want to pause, you can usually see the rudder from topsides, or run a line to check the hull for debris.

Weird story. I'd say anti-fouling paint could just be modded to include squid repellent, but the story doesn't fit and the skipper seems rather, how shall I put it...unaware. Based on the circumstances in the story it's probably best not to "jump" to conclusions.

I live on Nuku Hiva, the island that Shigeo stayed on his arrival. As I do repairs on visiting yachts, I was asked to look at his hydraulic steering which had sprung a leak.
Shigeo is over 70 and a late starter in single handing. (I had an email from him last week saying he had left Tarawa on the last leg to Japan.)
His boat is built to move, and, he did a really fast time from here to Raiatea, so, it wasn't his inability to sail fast that caused such a long voyage, it had to be something else.
It was not Shigeo who dived to look, as I was told, it was a skipper from another boat, a long-time sailor and doctor, so not prone to exaggeration.
these squid exist, it's possible......

On a different note I'm looking to contact a yacht leaving soon for Nuku Hiva as I have a request for something he could bring.
My email is philipbeardmore@mail.pf
Having arrived here by boat myself, some 13 years ago, I could also help with local knowledge.